1. Field of the Invention
This invention relates to a protector for a boot which covers the sliding face of a piston arranged to thrust a friction pad in a disc brake.
2. Description of the Prior Art
In a disc brake of the type arranged to provide a braking force by thrusting friction pads into contact with a disc by means of a piston in sildable engagement with a cylinder formed within a caliper body, it has been considered very important to maintain the piston smoothly slidable. Therefore, generally, the conventional disc brakes are provided with a bellows-like rubber boot arranged between the piston and the cylinder body in such a way as to shut out the external air from the sliding face of the piston. Meanwhile, the contacting surface on the disc and the friction pads produce friction heat in the region of the boot. A resultant high temperature then tends to cause a rupture of the boot or deterioration in its elasticity. To solve this problem, therefore, many prior art disc brakes have been arranged such that the disc confronting surface portion of the boot is covered with a protector and shielded thereby from thermal radiation.
The boot protectors of the prior art arranged to shield the boot from heat include a type arranged to serve the combined purpose of preventing brake noise and acting as a shim attached to the back metal of the friction pad. Another type is arranged to be attached to the fore end of the piston. The former type has the shortcoming that the boot protector itself tends to have a high temperature due to heat conduction. In the case of the latter type, on the other hand, the boot protector must be allowed to move together with the piston, and this necessitates a relatively complex structural arrangement for preventing the interference of a nearby member such as a support or the like. This complex structural arrangement causes complications in assembly and disassembly work.